1. Field of the Invention
The present invention relates to a multi-system air conditioner including a plurality of indoor units.
2. Description of the Related Art
Known in the art is a multi-system air conditioner which includes one outdoor unit and a plurality of indoor units and provides a heat pump type refrigerating apparatus among the units.
The multi-system air conditioner of this type can heat or cool a plurality of rooms in a house or a building at a time and is convenient in this sense.
In those buildings, however, some having a computer room, some having a perimeter zone and some having an interior zone, a cooling request comes from a given location or locations and, at the same time, a heating request comes from other locations.
In this case, it is not possible to operate the air-conditioner such that one of the heating and cooling requests is given a priority over the other.
There is a possibility that a better environment will be created at some location but that the workers in other locations will feel uncomfortable or apparatuses, such as computers, in still other locations will sometimes fail.
Such an unfavorable condition or conditions are liable to occur in the buildings or the common houses especially in an intervening season between the spring and the autumn.
An air conditioner as will be set out below has recently emerged which can operate at least one of indoor units in a cooling operation mode and one or more remaining indoor units in a heating operation mode. This type of air conditioner is shown, for example, in Published Examined Japanese Patent Application 61-45145.
When a cooling load is greater than a heating load in the air conditioners of this type, a heat exchanger in the indoor unit of a cooling operation mode serves as an evaporator and a heat exchanger in the indoor unit of the heating operation mode, as well as the outdoor heat exchanger, serves as a condenser.
When, on the other hand, the heating load is greater than the cooling load, the heat exchanger in the indoor units of the heating operation mode acts as a condenser and the heat exchanger in the indoor units of the cooling operation mode, as well as the outdoor heat exchanger, acts as an evaporator.
When the cooling load is substantially the same as the heating load, a stream of a refrigerant into the outdoor heat exchanger is stopped, allowing the heat exchanger in the indoor units of the heating operation mode to function as a condenser and the indoor unit of the cooling operation mode to function as an evaporator.
The use of such a type of air conditioner can eliminate a drawback as set forth above.
In the operation mode where the cooling load is substantially equal to the heating load, a refrigerant may sometimes be accumulated on the outdoor heat exchanger.
A short supply of a refrigerant through the respective indoor units may occur, causing a decline in a cooling or a heating capacity of their own.